The invention is directed to a method and apparatus for opening and emptying bags that contain recyclable materials prior to recovery of the recyclable materials.
Operators of facilities that process municipal solid waste (MSW), curbside collected recyclable materials, and other bagged waste materials have long noted the need for a machine that automatically opens and empties plastic trash bags. Contained within these plastic trash bags are typical household and commercial wastes, including valuable recyclable materials such as aluminum and steel cans, glass beverage containers, plastic containers, cardboard, and newspaper.
These plastic bags must be opened and emptied to permit sorting of the contents for recycling, composting, incineration, and/or other waste utilization or waste disposal treatment.
The ability to open and empty plastic bags automatically has several advantages over manual opening. Automatic opening reduces labor costs. Automatic opening also increases worker safety by reducing human contact with the unknown contents of a bag, such as hypodermic needles, broken glass, razor blades, and the like.
Mechanical systems exist which automatically open and/or empty plastic bags. Examples of these systems are illustrated in U.S. Pat. No. 4,533,053, issued to Kenny et al.; U.S. Pat. No. 4,533,054, issued to Sommer, Jr. et al.; U.S. Pat. No. 5,002,451, issued to Hale et al.; U.S. Pat. No. 4,995,770, issued to Crane; U.S. Pat. No. 4,798,508, issued to Lewis; U.S. Pat. No. 4,725,184, issued to Bennison; U.S. Pat. No. 4,515,509, issued to Frisz; and U.S. Pat. No. 4,344,268, issued to Wakamatsu et al..
These mechanical systems operate by exerting a dynamic force or a combination of dynamic forces on the bags by, for example, ripping, tearing, dropping, and/or breaking, to cause the bags to tear or otherwise rupture.
Unfortunately, these conventional systems damage the recyclable materials inside of the bags. This makes subsequent recovery of the contents of the bags difficult or impossible as a practical matter. For example, these conventional mechanical systems cause a great deal of glass breakage. The resulting shards of glass become embedded in paper, cardboard, textiles, and other materials, making these materials less valuable and/or less recoverable for recycling. The broken glass also gets into food wastes making production of a food waste compost product more difficult. The different colored broken glass becomes intermixed and therefore unrecoverable for the purpose of recycling the glass back into containers. Similar difficulties exist with other types of potentially recoverable materials when conventional opening and emptying devices are used.